About line 137 of templates/default/showflat.tpl you'll see the line for the tweet button:

Code

<a href="http://twitter.com/share?url={$facebookURL}&amp;via={$config.YOUR_TWITTER}" class="twitter-share-button" data-related="Mindraven">Tweet</a>

Change that to:

Code

<a href="http://twitter.com/share?url={$facebookURL}&amp;via={$config.YOUR_TWITTER}" class="twitter-share-button" data-related="Mindraven" data-count="none">Tweet</a>